Electromechanical transducers are machines which convert electrical energy into mechanical energy or vice versa, such as an electrical motor or a generator. While for example an electric motor converts electrical energy into mechanical energy, an electric generator converts mechanical energy into electrical energy. However, both types of electromechanical transducers use a magnetic field in conjunction with a conductor to achieve the energy conversion. In particular, a changing magnetic flux generated by the magnetic field may induce a voltage between points of the conductor resulting in a current representing electrical energy.
An electromechanical transducer may comprise a stator arrangement and a rotor arrangement. The stator arrangement may represent a stationary part of the electromechanical transducer, while the rotor arrangement may represent a part or parts of the electromechanical transducer moving relative to the stator arrangement, in particular rotating relative to the stator arrangement. The rotor arrangement thereby may comprise magnets, such as permanent magnets, which rotate relative to one or more coils comprised in the stator arrangement.
There are a number of different types of generators which differ in the direction of a major part of the magnetic field relative to a rotation axis of the rotor arrangement. In a so-called radial flux generator the magnetic field lines of the major part of the magnetic field are directed in a radial direction perpendicular to the axial direction representing the direction of the rotation axis of the rotor arrangement. In contrast, in a so-called axial flux generator the magnetic field lines of the major part of the magnetic field are at least approximately parallel to the axial direction. To achieve this direction of magnetic field lines the magnets comprised in the rotor arrangement have to be arranged appropriately. In particular, a connecting line connecting the two magnetic poles may be oriented at least approximately parallel to the axial direction.
Depending on the orientation of the magnets also the coils comprised in the stator arrangement must be arranged appropriately such that a magnetic flux penetrating through the coils is maximized. In particular, a small gap may be formed between magnets of the rotor arrangement and the coils of the stator arrangement.
An advantage of an axial flux generator may be that the magnetic flux is oriented along the axial direction of the rotor arrangement. This may substantially eliminate or reduce traditional cogging problems.
It may be important to keep the air gap between the magnets of the rotor arrangement and the coils of the stator arrangement constant so that an axial magnetic flux may be uniform for each of the magnets passing the coils of the stator arrangement. In order to maximize the efficiency of the generator the size of the air gap may be very small, such as a few millimeters. However, any misalignments and/or any movements or deflections of the rotor arrangement relative to the stator arrangement may result in alternating axial flux and may even result in damage of components of the generator. For generators having increased diameters this problem may be even more severe, as even a small misalignment of the rotation axis of the rotor arrangement may result to movements or deflections of radially outer parts which scale with the diameter such that an amount of these movements or deflections may not be tolerable or may lead to collisions of components of the rotor arrangement with components of the stator arrangement.
Document WO 2009/071843 discloses an axial flow electric rotary machine, wherein a filler material has been added in the air gap between rotating magnets and stationary coils.
However, it has been observed that conventional generators still suffer disadvantages in respect to efficiency and durability. There may be a need for a stator arrangement for an electromechanical transducer which, when used in an electromechanical transducer, improves operation of the transducer, in particular in respect to its efficiency and durability. Further, there may be a need for an electromechanical transducer which at least partly obviates problems observed in the prior art resulting from misalignments and/or deflections of the rotor arrangement relative to the stator arrangement.